Distributor



A Y Dec. 2, 1948. c. J. Fnl'cH ET AL DISTRIBUTOR C. J. FITCH ET AL DISTRIBUTOR De@ 21, 194s.

2 Sheets-Sheet 2 Filed Oct. 18', 1945 M 5 www m MTM N EME VJ N. .T MCR.. m

Patented Dec. 2l, 1948 Y., assif'gnors to International Business Machines Corporation; New York, N. Y., a corporation of New'York 1 Application-october 1s, 1945-, serial No.. 623,024L

19= Claims.

Thisv invention relates to" adistributor fory 1se tributing telegraphicsig-nal elements," the lieven-- tion bein-g an improvement,Y onV they distributor. shown in the patent to- CL J. Fitch", No. 21,210,574. Itsy principalE advantagewoverthe `distributor dis closed in this patent is its greater reliabilityA in op eration, due to theYV fact that the. signal elements are differentiated by sharp pulses, whichy can bev madeto come ast-the middle of 'each' signal element'. As compared with said patent the invention' is cliaract'erizedby a substitution of trigger tubes for the storage relays in theI patent; The. trigger tubes can be fired `more rapidlythan'. a. relay can' be energized-;v allowing/*shorter pulses. to be used? toE dierentiate the signal elements..

Accordingly, the mainf object of! theinvention` is to provide` an improved distributor particularlyv sui-ted? for distributing telegraphic signal elements .torespectve con-troldevices.-

Special features of theo-invention pertain to the means for starting the: distributor sweep" and'. thel means for.' restoring .the entire circuit' to normal` condition. at the end ot a siaveep...l

Other' object-slof the. invention. will; be pointed.

out. in the following' description claims andinlustrated in. the. accornpanyingA drawings, whichr disclose, byl Wayof examples, the principle of the invention.v and: the best modegwhich has.. beenl contemplated, of applyingth'at principle'.

In the.. drawings: Figs.. 1aA andlb are twoi parts: of.4 a.- complete'wir--Y ing. diagram.v tot a telegraph. receiver embodying,`

.the invention.`

Figs.. 2-6- are diagrams. of various signal'A and distributorwave shapes.. plotted on anI equaLti-me basis.` In*v particular :5

2' is a diagramafoi. farstandard six-unit tele*- graph code signalv composed of` marking and spacing signal elements.;

Fig.. 3 is. a diagramof the actual toney signal as received.

Fig. 4 is a diagram of the rectiiled signal which. controls the distributor;

Fig. 5' isv a 'diagram ol ther sweep'impulses. from .the plates of thesequence tubes;

Eig'. 6 is a diagram of the differentiatingimpulses derived fromthe sweep impulses.

For the purpose otillustration; theinvention isz shown` embodied in a receiver ofthe type disclosed in: Patenti No.. 21,210,574. Power is derived from. allOvolt A..C.. line..` through aplug.r I., the alten* hating current being krectified by a. full. wave se- 2f impressed-acrossthe' plates of' a condenser 3",.with the 'polarity indicated. Across this condenser is.l connectedk a voltage divider consisting, of resistors It',v 5, yE', T', and' 8; andk potentiometer 9'. From this voltage divider `various connections are made to supply the proper voltages to the tube circuits The A. C'. linealsc feeds a step down illament' transformer II, across' the secondary'of which the filaments of the tubes are connected in series multiple, as partially indicated at I2. The secondary of transformer I'I also' has connected across it a selenium rectifier I3'l which impresses al Voltage across a condenser" I4', of the` polarity indicated, which is used as' a ybias supply. A resistor III isv connected-across the terminals of the condenser' A completesignal, as shown in Fig, 2*, comprises a start signal, six code elements, and a stop signal.- AA signalhaving any other desired number of cod-e elementsv may be used, by a suitable alteration lof theV circuit. In' this complete signal the' start signal' is spacing; the code-elements I, 4, andt 5 aremarking, the code elements 2. 3, and 6-f arex spacing, and the stopsignal is marking. As

sli-own in Fig. 3', 'the spacing signals are-charac-V terized'by' tone andthe marking signals by' ali-- sence of tone'. Suchasignal is more eiiici'ent for keying a C. Wl radio frequency carrier on and off, as in this 'case' the Cl WQWillf be off during th stop period, or while-tlievmaciiineis idle. l

Tone signals; as shownfin Fig. 3", transmitted over 'any' communication channel, are fedinto a jack. F5. The-signals are impressed, through a .transformer'TBf and a volumefcontrol `I 6; upon theA grid ofE a vacuum tubellllf.` The plate of the tube VIII is connected' through' the prim-ary winding of' a*transformerI and through a voltage dropping resistor IIJ-and Wire ISf. to thep'ositive'end of the:

thevoltflge.y divider i4-9 While its plateI is Connectedi` through: the pri-maryI cfa. transformer 'El t and wire. I9to the positive end of the voltage di; vider 1 9. The am`^1ied output of tube VII ses: through transformer Tit to the plat@ ami;

w vacuum'. tube VIZ", which' is' hooked. upm' a half-wave rectifier. The cathode of tube Vl2 is connected by a wire 28 to a point 29 on the voltage divider 4 9. This tube rectifies the tone signai and the equivalent D. C. signal appears across a condenser 24. Connected across the condenser 24 is a noise lter inductance 25 in series with condenser 26, shunted by a resistor 21. The inductance 25 and condenser 2B forma low pass lter for removing any noise or impulses of shorter duration than the signal. The rectified signal, as it appears across the resistor 21, is approximately shown in Fig. 4.

Start circuit The negative end of resistor 21 which is shown, for the purpose of identification, as a terminal 23, is connected through a grid resistor to the grid of a vacuum tube VI3. The cathode of vacuum tube VI3 is connected by Wires 35 and 22 to the negative end of the bias resistor I9, while its anode is connected through a limiting resistor 36 and the primary coil of a transformer T12 to wire I9 and the positive end of the voltage divider 4 9. The point 29, to which the grid of tube VI3 is connected through grid resistor 30, resistance 21, and wire 29, is at a potential which normally renders the tube VI3 conductive, causing plate current to pass through the primary winding of transformer TI2. The start signal depresses the potential on the grid of tube i VI3 and cuts off the plate current.

` The interruption of the plate current through transformer Tl2 induces an E. M. F. in the secondary winding, one side of which is connected through wires and 22 to the negative end of the bias resistor I9, while the other side is connected through a delay circuit comprising condensers 31 and 38 and resistor 39 to the control grid of a gas tube G9. The cathode of the latter tube is connected to the lower end of the voltage divider 4 9, while its anode is connected through a vacuum tube V9, resistance 40 and wire 4|, to a point 42 between the resistors 5 and 6. The grid of the tube V9 is connected through a grid leak resistor 43 to its cathode and this tube is accordingly normally conditioned to pass current. The voltage of the impulse induced in the secondary of transformer TI2, when the tube VI3 is cut off by the start signal, is such that it drives the control grid of gas tube G9 positive and fires the tube. The resistor condenser combination 31 39 is selected so as to have an RC time delay constant that will delay the firing of tube G9 for a period equal to about half the duration of the start signal of Fig. 4. Thus, at time A" (Fig. 4) tube G9 will fire.

A vacuum tube V8 has its anode connected through the primary winding of a transformer 'I to wire I9 and the top of voltage divider 4 9, while its cathode is connected by wire 4I to the point 42 of the voltage divider. The grid of tube V8 is connected through resistor 40 to its cathode and this tube is normally conductive. When the tube G9 fires, current flows through the resistor 40, causing a potential drop, as indicated, at resistor 49 and biasing off the tube V8. The eld of transformer T collapses and an E. M. F. is induced in its secondary winding. This starts the sweep impulses, as will now be described.

One end of the secondary winding of transformer T is connected by a wire 45, through the arm of potentiometer 9, to a selected point on the resistance of this potentiometer. The other end of the secondary winding of transformer T is connected, as indicated by the letters X (see also Fig.

1b) to the grid of the first tube Vl of a sequence of tubes VI V1. The cathodes of these tubes are connected by a wire 46 to a point 41 on the voltage divider 4 9. The anodes of tubes VI V6 are connected through the primary coils of related sequence transformers Ti-TS and a wire 48 to a point 49 on the voltage divider 4 9. The anode of tube V1 is connected through a resistor 50 to the wire 48. The grids of tubes V2 V6 are connected through the secondary windings of the preceding sequence transformers TI T5 and wires 5| and 45 to the arm of potentiometer 9. The grid of tube V1 is connected through the secondary winding of transformer T8 to a point 52 on voltage divider 4 9, as indicated by Y Y. Normally, the grids of the tubes VI V1 are biased negatively, as shown by the connections just traced, and the tubes are non-conductive.

The sequence of tubes VI V1, intercoupled by transformers TI T6, operates according to a principle described more fully in the copending application of C. J. Fitch, Serial No. 465,604, filed November 14, 1942, now Patent Number 2,421,606. When a sweep is initiated the sequence tubes V| V1 become conductive in succession, as shown in Fig 5, each tube returning to non-conductive condition as the next tube becomes conductive. The tubes Vil-V6 pertain, respectively, to the 6 elements of the code. The tube V1 initiates the restoring of the circuit.

The voltage induced in the secondary of transformer T when the tube V8 is cut off is of such polarity and amplitude as to swing the potential of the grid of the tube VI positive and render the tube conductive (see Fig. 5). Plate current starts to flow through this tube and the primary of transformer Tl. At this time the secondary of transformer TI has induced in it an E. M. F. which drives the grid of tube V2 more negative,

t causing no change in the conductivity of the latter. When the grid of tube Vi swings positive, grid current flows and retards the collapse of the field in the transformer T. At the time indicated by B in Fig. 5, the potential on the grid of the tube Vl drops to cathode potential and grid current ceases to flow, whereupon the eld in the transformer T collapses suddenly and the tube VI is cut oir abruptly. When the current through the primary coil of transformer TI stops, a voltage is induced in the secondary winding of this transformer which swings the potential of the grid of the tube V2 above cathode potential and this tube begins to conduct, as indicated at B in Fig. 5. Grid current flows through the secondary winding of transformer Ti, delaying the collapse of the eld in this transformer. At the time indicated by the letter C in Fig. 5, the potential on the grid of tube V2 passes below cathode potential and grid current ceases, causing the field in the transformer TI to collapse suddenly, cutting off the tube V2.

In a similar way the remaining tubes V3-VB become conductive in succession, as shown in Fig. 5.

Associated With each tube VI V6 is a trigger tube GI-GB, preferably of the thyratron type. The cathodes of these trigger tubes are connected by a wire 55 to the negative end of the Voltage divider 4 9. Their plates are connected through respective arc holding resistors 56 and wire 51 to the positive end oi the voltage divider 4 9. Their control grids are connected by resistors 58 and a wire 59 to the negative end of the resistor I0. The bias on the control grids therefore normally prevents these tubes from turing'. The shield.r grids.- of the. tubes.` Gle-'G6 are connected; through. current limiting resistors 60, wire. 6.1, resisten 2:1.L and. wire 28 to the point 2@ on. the. voltage divider Il-49.. When no signal is' passing through resistor 21,. the; bias on the shield grids of. the tubes GI.-G6 is such as to allow these tubes to be red if. the potential on. theircontrol. grids` is raised to a suitable. point'r butidt signal current is passingthrough. resistorv 215th'e" tubesA Gi-G-' are biased oiv so aste be. unintluenced by positive impulses applied. to their control.A grids. The circuit proportions' are such thatfany signal which. has suicient. amplitude. tri-'start the sweep will biasy the shield grids` of tubes; Gil-G6, lto prevent them fromV being' tired byposi-tive.impulsesapplied to their control grids. @Thecontrola grid oi each tube GiG6 is. cou.- piedabyacondenser B2 and awire 63 to a tap on the.y primary coil of thev related transformer Til-T6.. At the successive times indicated by the l'ettersB'-G in Fig. 6when`current through thefpriimary` coils of transformers TI-TB stops, positive impulses are transmitted through the condensers 62 toy thecontrol grids of the tubes G|-G6L If, at the time the` control grid of anyone of these tubes receives such a positive impulse theV potential on the shield grid of that tubeis high, due tov an absence of signalr current in the resistor 21?, the tube will be red. For example, at the time B" (Fig. 4) there is zero signal current in the resistor 21, and consequently the positive pulse B (Fig. 6) res the tube GI, its arc being held by current flowing through resistor it'.v At the time C" (Fig. 4), signal current is flowing in the resistor 21 and the shield grids of all of the tubes G'2-G6 are biased to a potential which renders these tubes non-responsive to positive pulses applied' to their' control grids; Consequently, the positive' pulse (Fig. 6)' transmittedE from the transformerTEA to the control"v gridof the tube G2 at this time does' not. fire the tube G2. In a similar manner as the remaining signal elements come in, the tube G3" is noty iiredthe tubes `G4 and G5' arevfired, while the tube` GGfis not fired. Thus,lcorresponding to thefsign'al'j shown inrFig'. 2 the tubes GI', G4 and G5"` remain conductive at theend of'the sweep andthe other tubes remain non-conductive.`

n There is a separate tube Gi, G2', G6 for eachwcod'e signal element. The potential `iin-- pressed upon the control grid of each of the tubes GI`XG6 varies betweenv a low potential which will prevent thetube. from'being red' by a high potential applied to its shield grid, and a high potentialwhich willr allow the tube to be iiredv by 'a high potential appliedto its shield grid. vThe low potential'. on the control grid isthe normal'. bias..

whiletheihigh potential. is causedy by a sharply peaked impulse transmitted from the .related sweep .transformer Tlv, T2, .d T6 and occurs at a different time fory each tube, coinciding with. the reception. of the related `code signalelement.. Thisimpulse unlocks the tubeso` that it is responsi've tota high potential applied to its shield.

ing-lon spacing character. Any tube having a.

hignpotenual @nits shield grid. at the time its control grid goes to a high potential willbe fired,

awa-,eee

si'eldgrid when its. controlgrii goes to a. highs potential wiliefnot be fired..

The pulse: F (.Fig. 6) is transmitted not only to the control grid of tube G5 but also, through av` wire 64y and condenser 65,. to the control'. grid of the gas; tube G1. The cathode` and shield of: this tube: are. connected t'othe wire4 55,', whiile itsplate is connected through a relay coil Rif-toV the vwire: 51.V The control grid. is connected through resistor 6B to wire 59 which leads to the negative end oi. the: resistor lil.` The' normal` potential on. the; control grid of the tube G1 there-y fore biases the' tube off, but since the shiedgrid has zero bias the positivel pulse. F" transmitted tothe control grid iires the` tube, energizing. the relay Rl'.

` ThercontactsRta: to Rlf ci the relay Rl closeV at about the time G' (Fig. 6) due. tol the time. required; for thelrel'ay to become energized. When thisoccurs, circuits are extended from the` plates of. the tubes Gi-G through related control mag nets M.|M6= and the corresponding contacts Riina-Rif, to the wire5z1.. Only the control Inag-4 netsfconnected to the plates of tubes which have been. fired will be energized, inthe example given the magnetsMl, M4', and M5'. The control magnets may be, for example, the selector magnets ofthe telegraph printer shown in Patent No. 2,181,940; When they are energized, the telegraphprinter prints a character or: executes a function, corresponding to thecod'e combination. represented by' the magnets energized.

The top end: of. the secondary winding. of trans former' T62 is connected to a. pointron the voltage. dividerl 4'-.9` which is. higher than that point. to whichx the top` ends ofthe secondary windings of the transformers TI--T5y are connected. Conse-v quently. the normal. bias'lon the grid. of the tube. V1`is less negative than that on the grids of. the" tubes VI--Vl This causes a larger grid currenty toiiow and delays the cut-off of the tube V1 longer.' than that of: the tubes 'VI-V6. As; indicated' in. Fig. 5, the tube V1 remains conductive'` from the time G to the; time H, approximately twice as long as the other sequence tubes.. When the tube V1 becomes conductive, it transmits. a negative pulse, as indicatedbyA the letters' Z--Z (see also Fig. la), through a condenser 68 to they grid of tube V9, rendering the same non-conductive. This opens` the circuit through the tube. G9: and; its arc. is extinguished, restoring the starting' circuit to normal condition. The. value.

of condenser 68 is suchY that the negative impulse impressed `upon the grid of tubeV V9' lasts .for about one' signal element. During the sweep', while tube G9 remained'` conducting, additional signals impressed upon the `grid oftubey VIS.

causedno furthereffect.

the-'timefH- in Fig. 5, it transmits a positive pulse. through a condenser 69 to the control grid of the. gas tube G8. The cathode andv shield grid. of this tube are connectedtowire and its anode, throughlresistor 10, to wire 51.. The control grid isv connected through a resistor 1| to wire 59,. which causes the tube G8 to be normally biased off; The positive pulse transmitted through con denser 69 fires the tube G8 and a negative pulse.l is transmitted from its plate through a condenser 12 tothe plateof tube G1, extinguishing thev arc: of this tube. The relay R1 is deenergzed andi its: contacts Ria-RU open at about poi-nt 0 in Fig. 6, deenergizing the control magnetsMl, M4, and. M5, which; had been. energized.A The. inductance while any tube. havinga. low potential. .its 75 ofy the. coil of relay Rl, together with thecouplifn:

7 condenser 12 and resistor 10, form an oscillatory circuit. When relay Rl is deenergized, an oscillation is set up, the first negative wave of which is suicient to extinguish tube G8.

Likewise, oscillatory circuits are formed by the coils of magnets MI-MB, spark suppressor condensers 13 and resistances 14 and resistances 5S. When the magnets Ml, M4, and M5 are deenergized, oscillatory currents are set up in the respective oscillatory circuits, the first negative wave of which extinguishes the respective gas tubes GI, G4 and G5. The distributor circuits are thereby restored to normal condition, ready to receive the next signal impulse.

The entire circuit is restored within a time duration of one signal element so that the stop signal may be as short as one signal element. In Figs. 2-6 the stop signal is ll/g signal elements.

The variable potentiometer 9 allows the bias on the sequence tubes Vl-V6 to be adjusted so that the time of the sweep can be varied to match or be in phase with the incoming signals. The variable resistor 8 is locked in adjustment at a position that will give accurate timing when resistor 9 is set at the middle of the range. Any tendency of the sweep impulses to be lengthened by an increase in the anode voltage caused by a variation in the line voltage supply is compensated for by a tendency of the impulses to be shortened because of an increase in bias and heater voltage. proportion of the plate voltage and bias voltage and the characteristics of the sequence transformers are such that variations in line voltage supply of the order of plus or minus 10% have virtually no effect on the timing of the circuit.

The duration of the sharp differentiating impulses B-G (Fig. 6) may be of the order of 1% of a signal element. By adjustment of potenti ometer 9 these impulses are made to unlock the distributor tubes GI-GB for only a short time during the arrival of the center portions of the received signal elements. This allows for a maximum drift, or phase shift, of the incoming signals, and maximum signal distortion, before failure occurs.

It is evident that the distributor can be adapted to a code of any number of code elements, by changing the number of sequence tubes VI-V6, sequence transformers Tl-T5, storage tubes GIG6, and control magnets Ml-MB.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art. without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. In a receiver for receiving combinational code signals, a set of gaseous trigger tubes, one for each code signal element, each tube having at least a first and a second grid, means normally impressing upon the rst grids of all of said tubes a biasing potential sufficiently negative to prevent said tubes from being red by high potentials applied to their second grids, means operating in response to the received signal for applying concurrently to the second grids of all of said tubes, high or low potentials, in dependence upon the marking or spacing character of the successive code signal elements, and means for The f 8 lifting the potential on the first grids of the tubes in succession, each at the time of reception of the related signal element, whereby each tube will be fired in which the lifting of the potential on its first grid finds a high potential on its second grid, due to a marking signal element.

2. In a receiver for receiving combinational code signals, a set of gaseous trigger tubes, one for each code signal element, each tube having at least a first and a second grid, means normally impressing upon the first grids of all of said tubes a biasing potential sufficiently negative to prevent the tubes from ring when a high potential is applied to their second grids, signal receiving means having an output terminal on which the potential is high during marking signals and low during spacing signals, means connecting said terminal to all of the second grids of said tubes, a sweep circuit comprising means to transmit t0 the first grids of said tubes in succession, at intervals of one clement, positive impulses adapted to render said tubes successively responsive to a high potential on their second grids, and means responsive to a start signal preceding each code signal for initiating an operation of said sweep circuit at such time that said positive impulses will coincide with respective code signal elements.

3. A receiver as described in claim 2, wherein said positive impulses are sharply peaked, having a width of only a small fraction of a signal element.

4. A receiver as described in claim 2, wherein said positive impulses are sharply peaked, having a width of only a small fraction of a signal element, and means are provided to adjust the interval between said impulses, to bring them to the center of the respective signal elements.

5. A receiver as described in claim 2, wherein said sweep circuit comprises a sequence of vacuum tubes intercoupled by transformers and supplied from a voltage divider fed by a line across which the voltage may vary, said sequence tubes having grids, cathodes, and anodes connected to successively higher points on said voltage divider,

whereby any increase in line voltage causing a higher anode potential will be compensated by a greater bias on the grids of said sequence tubes.

6. In a distributor, a set of gaseous trigger tubes, each having at least a cathode, an anode, a rst grid, and a second grid, a voltage source, means forming two circuit paths between the anode of each of said tubes and said voltage source, one of said circuit paths being normally closed and including a resistance, the other including a control magnet and a normally open contact in series, means connecting the cathodes and both grids of each of said tubes to said voltage source so that each grid has a bias voltage which will, by itself, prevent the tube from firing, means for lifting the potential on the first grid of each of said tubes in succession, means for lifting the potential on the second grids of all of said tubes concurrently with the lifting of the potential on the first grids of selected ones of said tubes, whereby those tubes in which a coincidence of high voltages on both grids occurs will be fired and their arcs held through the respective normally closed circuit paths, and means for finally closing said contacts, thereby energizing the control magnets pertaining to tubes which have been fired.

7. In a receiver for receiving combinational code signals, a set of gaseous trigger tubes, namely, a signal tube for each code signal element and a print control tube, each tube having at least an anode, a cathode, a first grid, and a second grid.

9 .a voltage source, means including larelay coil con- :necting the anode of said print control tube to vsaid 'voltage source, means forming two circuit vpaths between the anode of each of said signal tubes and said voltage source, one of said circuit paths :being normally closed and including a resistance, theother including, in series, a selector magnet and a normally open contact pertaining to said relay, means connecting the cathodes and both `grids vof each of said signalv tubes to `said voltage vsource so that each grid has a .bias voltage'which will, by itself, prevent the tube from firing, means vconnecting the cathode and the .grids of said print control tube to saidvoltage source :so that the second grid of said print control tube has approximately a zero'bias and the first grid -has a negative bias which will prevent the tube from fir-ing, means for lifting the potential on the lirst grid of each oi said signal tubes in succession, to

unlock said signal tubes at successive timescolnciding with successive elements of a signal, signal receiving means, means controlled by said receiving means for lifting the potential on the ysecond grids of all of `said signal tubes concurrently during the reception of marking signal elements,

whereby those signal tubes in which a coincidence of high voltages on both grids occurs will be fired and their arcs held through the respective normally Vclosed circuit paths, and means for lifting the potential on the iirst grid of said print con-- trol tube, whereby the latter will be fired and said relay energized approximately concurrently with the unlocking of the last signal tube.

8. In a distributor as described in claim p6, means to open said contacts, the contact in yseries with each of said magnets being shunted by a spark lsuppressing condenser, forming an oscillatory circuit including said condenser, the coil of lthe related magnet, and the resistance in the related normally closed circuit, whereby, when said contacts are opened, oscillatory discharges are set up in the oscillatory circuits pertaining to any of said tubes in a conductive state, the first negative Waves of which extinguish the respective tubes.

9. In a receiver for receiving combinational code signals of the type in which spacing signal velements are represented by an oscillating voltage wave and marking signals are represented by an absence of an oscillating voltage wave, a set of gaseous trigger tubes, one for each code signal element, each tube having at least a cathode, an anode, and first and second grids, a source of voltage, means connecting the cathode, anode, and grids of each of said tubes to said voltage source so that the first grid of each tube has a negative bias which will prevent the tube from being fired and so that the second grid of each tube has a positive bias, signal receiving means comprising a rectifier and a resistance in series therewith, said resistance also being in series with the connection of the second grids of said tubes to said voltage source, the current through said rectifier and resistance during spacing signal elements generating a voltage drop across said resistance of suflicient magnitude to bias the second grids of said tubes negatively and prevent said tubes from firing, a sweep circuit comprising means to transmit to the first grids of said tubes in succession, at intervals of one signal element, positive impulses adapted to render said tubes successively responsive to a high potential on their second grids, and means responsive to a spacing start signal preceding each code signal, for initiating an operation of said sweep circuit at such ztinfiethatsaid positive impulses will coincide with respectve code signal elements.

10. A receiver as `described in claim 9, wherein filtering meansare placed in the circuit of said -rectiier and resistance.

11. In adistributor, a sequence of Vacuum tubes having rat least a cathode, an anode, and a grid, intercou-pled by transformers so that each tube, 'except the first, is made conductive in sequence by an impulse transmitted to its grid through a related transformer `from the plate vof ythe prefcedi-ng tube, 'when the latter becomes non-conductive, a voltage source to which the cathode, anode, and grid of Veach tube are connected so that the first tube of the sequence is normally conductive -and the other tubes are normally non-conductive, -a gaseous trigger 4tube for starting a sequence, means connecting ythe electrodes of said starting tube -to said voltage source so that said starting tube 4Tis normally non-conductive, means for receiving signals,'means operated by said receiving means, `onrecei-ving a start signal, for iiring said star-'ting tube, means controlled by the current through -said starting tube for biasing off said normally conductive first sequence tube for so long yas current flows through said starting tube, thereby starting the sequence, and means controlled by the last sequence tube for extinguishing said starting tube.

12. A distributor as described in claim 11, wherein said `starting tube has an anode connected to said voltage source through the platecathode circuit path of an extinguishing vacuum tube having `a grid, the grid of said 4extinguishing vacuum `tube being coupled to the lanode of the last sequence tube so as to be biased to a cut off potential under control of said last sequence tube.

' 13. A distributor as Vdescribed in claim 11, wherein the grid Aand cathode of said first sequence tube are interconnected by a resistance, said starting tube having an anode conductively coupled to the grid end of said resistance, whereby when said starting tube is fired a voltage drop is produced in said resistance which biases oil? said first sequence tube.

14. In an electrical circuit, a voltage source, a gaseous trigger tube having an anode and a cathode connected to said voltage source the anode connection including a resistance, an inductance and a capacitance serially connected across said resistance to form an oscillatory circuit therewith, and means to start oscillations in said oscilconnected to the anode of said tube and the adjacent end of said resistance, means to lift the potential on said grid to lire said tube, normally open contact means to connect the other end of the Winding of said electromagnet to said voltage source, to energize said electromagnet when said tube is conductive, and means to open said contact means to deenergize said electromagnet and to start oscillations in said oscillatory circuit, the first negative wave of which will extinguish said tube.

16. In an electrical circuit, a voltage source, two gaseous trigger tubes, each having an anode, a cathode, and a grid connected to said voltage source so that the tubes are normally biased oi, the anode connection of one of said tubes including an inductance, the anode connection of the other one of said tubes including a resistance, a condenser coupling said anodes and completing an oscillatory circuit including said inductance and said resistance, means for momentarily lifting the potential of the grid of said first tube to re the same, and means for momentarily lifting the potential of the grid of said second tube to Ilre the latter, thereby extinguishing said rst tube by a negative impulse transmitted through said condenser, and setting up oscillations in said oscillatory circuit, the first negative wave of which extinguishes said second tube.

17. In a distributor, a set of gaseous trigger tubes each having a plurality of electrodes including a plate, a cathode, and at least a first and a second grid, a voltage source, means connecting said electrodes to said voltage source, so that each tube is normally biased ofl by the potential on its first grid, means operating at differential times to raise the potential on the first grid of each of said tubes in succession, and means for changing the potential on the second grids of all of said tubes in unison, between a cut-ofi potential and a potential which will render the tubes responsive to the potentials on their iirst grids, the changes occurring at selected intervals between said difterential times.

18. In a distributor, a sequence of high vacuum tubes, each of said tubes having a plurality of electrodes including a plate, a cathode, and a grid, a voltage source, means connecting said electrodes to said voltage source so that the rst of said sequence tubes is normally biased on and the rest of said sequence tubes are normally biased ofi, means coupling said sequence of tubes in cascade so that as each tube becomes non-conductive the next lower tube in the sequence will be made conductive, a gaseous trigger tube having electrodes including a plate, a cathode, and a control electrode connected to said voltage source so that said trigger tube is normally biased off, means to change the bias on the grid of said trigger tube to ignite the same, means conductively coupling the plate of said trigger tube to the grid of said rst sequence tube so that the latter is biased oiI as said trigger tube is ignited and remains biased off as long as said trigger tube is conductive, and means controlled by the last of said sequence of tubes for extinguishing said trigger tube.

19. A distributor as described in claim 18, wherein the means for extinguishing said trigger tube includes a normally conductive extinguishing vacuum tube in the plate connection of said trigger tube to said voltage source, and means controlled by the last sequence tube for biasing oif said extinguishing vacuum tube.

CLYDE J. FITCH. ROBERT N. EICHORN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES IATENTS Number Name Date 1,793,329 Langmuir Feb. 17, 1931 2,049,376 Hertwig et al July 28, 1936 2,099,065 Holden Nov. 16, 1937 2,210,574 Fitch Aug. 6, 1940 2,272,070 Reeves Feb. 3, 1942 Certificate of Correction Patent No. 2,456,825. December 21, 1948.

CLYDE J. FITCH ET AL.

It is hereby certied that error appears in the printed specication of the above numbered patent requiring correction as follows:

Column 8, line 21, claim 2, after the Word one insert signal;

and that the said Letters Patent should be reed with this correction therein that the same may conform to the record of the case in the Patent OHice.

Signed and sealed this 24th day of May, A. D. 1949.

THOMAS F. MURPHY,

Assistant Uommzssoner of Patents.

Certificate of Correction Patent No. 2,456,825. December 21, 1948.

CLYDE J. FITCH ET AL.

It is hereby certied that error appears in the printed specication of the above numbered patent requiring correction as follows:

Column 8, line 21, claim 2, after the Word one insert signal;

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 24th day of May, A. D. 1949.

[IML] THOMAS F. MURPHY,

Assistant Uommzssz'oner of Patents. 

